The betaines are a special class of zwitterions. These materials are self neutralized and contain no counterions. Moreover, the positive and negative charges are separated by alkyl groups.
Saturated nonpolymerizable betaines are well known in the detergent and fiber fields. Both carbonyl and sulfo-saturated betaine compounds are claimed in such patents as U.S. Pat. Nos. 3,649,677; 4,088,612; 3,539,521; and 4,381,980.
Polymerizable monounsaturated carboxy betaine monomers, e.g., carboxymethacrylate betaine monomers (I) and polymers (II) are well-known and disclosed in U.S. Pat. No. 2,777,872 (Jan. 15, 1957), U.S. Pat. No. 2,834,758 (May 13, 1958) and U.S. Pat. No. 2,846,417 (Aug. 5, 1958). ##STR1##
Carboxyvinylpyridine betaine monomers and homopolymers (II) have also been reported [H. Ladenheim and H. Morawetz, J. Poly. Sci. 26, 251 (1957)]. ##STR2##
Polymerizable monounsaturates sulfoalkyl betaine monomers such as: ##STR3## are taught in such patents as U.S. Pat. Nos. 3,547,985, 3,473,998, 3,484,479 and Ger. Auslegeschrift No. 1,207,630, and in such articles as Hart and Timmerman, J. Olym. Sci. 28 118 (1958) and Galin Polymer 25 121,254.
Cyclopolymerizable alkyl quaternary ammonium salts, e.g., ##STR4## wherein R' and R" are alkyl groups, are described in the article by Butler [J. Am. Chem. Soc. 79 3128 (1957)].
Cyclopolymerizable N-carbomethoxymethyl-N-alkyl-N-N-diallyl ammonium chloride, ##STR5## is described in Eur. Pat. Ep No. 55,048 (June 30, 1982). The above monomer cyclopolymerizes to form polymers of the type, ##STR6## These polymers in turn, can be hydrolyzed to form cyclo carboxy betaine polymers ##STR7## where are useful as antimicrobial polymers.
N-Na carboxylate-N-methyl-N-N-dialkyl ammonium betaine monomer is disclosed in U.S. Pat. No. 2,935,495 by the reaction of N-methyl-N-N-diallylamine with the sodium salt of bromoacetic acid. However, the preparation of this monomer requires mixed solvents and several steps (i.e., preneutralization of the bromoacid reaction with the tertiary amine and extraction with benzene) and mixed solvents (H.sub.2 O/acetone). ##STR8##